From: "Eric W. Biederman" <ebiederm@xmission.com>
To: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
Kees Cook <keescook@chromium.org>,
linux-api@vger.kernel.org,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH 13/17] signal: Make individual tasks exiting a first class concept
Date: Mon, 3 Jan 2022 15:33:08 -0600 [thread overview]
Message-ID: <20220103213312.9144-13-ebiederm@xmission.com> (raw)
In-Reply-To: <87r19opkx1.fsf_-_@email.froward.int.ebiederm.org>
Add a helper schedule_task_exit_locked that is equivalent to
asynchronously calling exit(2) except for not having an exit code.
This is a generalization of what happens in de_thread, zap_process,
prepare_signal, complete_signal, and zap_other_threads when individual
tasks are asked to shutdown.
The various code paths optimize away the setting sigaddset and
signal_wake_up based on different conditions. Neither sigaddset nor
signal_wake_up are needed if the task has already started running
do_exit. So skip the work if PF_POSTCOREDUMP is set. Which is the
earliest any of the original hand rolled implementations used.
Update get_signal to detect either signal group exit or a single task
exit by testing for __fatal_signal_pending. This works because the
all of the tasks in group exits are killed with
schedule_task_exit_locked.
For clarity the code in get_signal has been updated to call do_exit
instead of do_group_exit when a single task is exiting.
While this schedule_task_exit_locked is a generalization of what
happens in prepare_signal I do not change prepare_signal to use
schedule_task_exit_locked to deliver SIGKILL to a coredumping process.
This keeps all of the specialness delivering a signal to a coredumping
process limited to prepare_signal and the coredump code itself.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/coredump.c | 7 ++-----
include/linux/sched/signal.h | 2 ++
kernel/signal.c | 36 +++++++++++++++++++++---------------
3 files changed, 25 insertions(+), 20 deletions(-)
diff --git a/fs/coredump.c b/fs/coredump.c
index 09302a6a0d80..9559e29daada 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -358,12 +358,9 @@ static int zap_process(struct task_struct *start, int exit_code)
start->signal->group_stop_count = 0;
for_each_thread(start, t) {
- task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
- if (t != current && !(t->flags & PF_POSTCOREDUMP)) {
- sigaddset(&t->pending.signal, SIGKILL);
- signal_wake_up(t, 1);
+ schedule_task_exit_locked(t);
+ if (t != current && !(t->flags & PF_POSTCOREDUMP))
nr++;
- }
}
return nr;
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index b6ecb9fc4cd2..7c62b7c29cc0 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -427,6 +427,8 @@ static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
}
+void schedule_task_exit_locked(struct task_struct *task);
+
void task_join_group_stop(struct task_struct *task);
#ifdef TIF_RESTORE_SIGMASK
diff --git a/kernel/signal.c b/kernel/signal.c
index 2a24cca00ca1..cbfb9020368e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1056,9 +1056,7 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
signal->group_stop_count = 0;
t = p;
do {
- task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
- sigaddset(&t->pending.signal, SIGKILL);
- signal_wake_up(t, 1);
+ schedule_task_exit_locked(t);
} while_each_thread(p, t);
return;
}
@@ -1363,6 +1361,16 @@ int force_sig_info(struct kernel_siginfo *info)
return force_sig_info_to_task(info, current, HANDLER_CURRENT);
}
+void schedule_task_exit_locked(struct task_struct *task)
+{
+ task_clear_jobctl_pending(task, JOBCTL_PENDING_MASK);
+ /* Only bother with threads that might be alive */
+ if (!(task->flags & PF_POSTCOREDUMP)) {
+ sigaddset(&task->pending.signal, SIGKILL);
+ signal_wake_up(task, 1);
+ }
+}
+
/*
* Nuke all other threads in the group.
*/
@@ -1374,16 +1382,9 @@ int zap_other_threads(struct task_struct *p)
p->signal->group_stop_count = 0;
while_each_thread(p, t) {
- task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
count++;
-
- /* Don't bother with already dead threads */
- if (t->exit_state)
- continue;
- sigaddset(&t->pending.signal, SIGKILL);
- signal_wake_up(t, 1);
+ schedule_task_exit_locked(t);
}
-
return count;
}
@@ -2706,12 +2707,12 @@ bool get_signal(struct ksignal *ksig)
for (;;) {
struct k_sigaction *ka;
+ bool group_exit = true;
enum pid_type type;
int exit_code;
/* Has this task already been marked for death? */
- if ((signal->flags & SIGNAL_GROUP_EXIT) ||
- signal->group_exec_task) {
+ if (__fatal_signal_pending(current)) {
ksig->info.si_signo = signr = SIGKILL;
sigdelset(¤t->pending.signal, SIGKILL);
trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
@@ -2719,8 +2720,10 @@ bool get_signal(struct ksignal *ksig)
recalc_sigpending();
if (signal->flags & SIGNAL_GROUP_EXIT)
exit_code = signal->group_exit_code;
- else
+ else {
exit_code = 0;
+ group_exit = false;
+ }
goto fatal;
}
@@ -2880,7 +2883,10 @@ bool get_signal(struct ksignal *ksig)
/*
* Death signals, no core dump.
*/
- do_group_exit(exit_code);
+ if (group_exit)
+ do_group_exit(exit_code);
+ else
+ do_exit(exit_code);
/* NOTREACHED */
}
spin_unlock_irq(&sighand->siglock);
--
2.29.2
next prev parent reply other threads:[~2022-01-03 21:34 UTC|newest]
Thread overview: 137+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 20:17 [PATCH 00/10] Removal of most do_exit calls Eric W. Biederman
2021-12-08 20:25 ` [PATCH 01/10] exit/s390: Remove dead reference to do_exit from copy_thread Eric W. Biederman
2021-12-12 17:48 ` Heiko Carstens
2021-12-13 14:50 ` Eric W. Biederman
2022-01-05 4:25 ` Al Viro
2021-12-08 20:25 ` [PATCH 02/10] exit: Add and use make_task_dead Eric W. Biederman
2022-01-05 5:01 ` Al Viro
2022-01-05 20:46 ` Eric W. Biederman
2022-01-05 21:53 ` Al Viro
2022-01-05 22:51 ` Linus Torvalds
2022-01-05 23:34 ` Al Viro
2021-12-08 20:25 ` [PATCH 03/10] exit: Move oops specific logic from do_exit into make_task_dead Eric W. Biederman
2022-01-05 5:48 ` Al Viro
2022-01-06 7:08 ` Al Viro
2022-01-07 3:42 ` Al Viro
2022-01-07 19:02 ` Eric W. Biederman
2022-01-07 18:59 ` Eric W. Biederman
2022-01-17 8:05 ` Christoph Hellwig
2022-01-17 12:15 ` Heiko Carstens
2022-01-17 13:17 ` Christoph Hellwig
2022-01-17 13:24 ` Arnd Bergmann
2022-01-17 13:27 ` [PATCH] microblaze: remove CONFIG_SET_FS Arnd Bergmann
2022-02-09 13:50 ` Michal Simek
2022-02-09 13:52 ` Christoph Hellwig
2022-02-09 14:03 ` Michal Simek
2022-02-09 14:40 ` Arnd Bergmann
2022-02-09 14:44 ` Michal Simek
2022-02-09 14:54 ` Arnd Bergmann
2022-02-09 23:31 ` Stafford Horne
2022-02-11 0:17 ` Stafford Horne
2022-02-11 16:59 ` Arnd Bergmann
2022-02-11 17:46 ` Linus Torvalds
2022-02-11 20:57 ` Arnd Bergmann
2022-02-11 21:10 ` Eric W. Biederman
2022-02-11 22:21 ` Stafford Horne
2022-02-14 7:41 ` Christoph Hellwig
2022-02-14 7:50 ` Christoph Hellwig
2022-02-14 16:20 ` Arnd Bergmann
2021-12-08 20:25 ` [PATCH 04/10] exit: Stop poorly open coding do_task_dead in make_task_dead Eric W. Biederman
2022-01-05 5:58 ` Al Viro
2022-01-05 22:33 ` Eric W. Biederman
2021-12-08 20:25 ` [PATCH 05/10] exit: Stop exporting do_exit Eric W. Biederman
2022-01-05 6:02 ` Al Viro
2022-01-05 22:36 ` Eric W. Biederman
2021-12-08 20:25 ` [PATCH 06/10] exit: Implement kthread_exit Eric W. Biederman
2022-01-07 2:27 ` Al Viro
2022-01-08 18:35 ` Eric W. Biederman
2022-01-08 22:44 ` David Laight
2022-01-10 15:00 ` Eric W. Biederman
2022-01-09 3:27 ` Al Viro
2022-01-10 15:05 ` Eric W. Biederman
2021-12-08 20:25 ` [PATCH 07/10] exit: Rename module_put_and_exit to module_put_and_kthread_exit Eric W. Biederman
2021-12-08 20:25 ` [PATCH 08/10] exit: Rename complete_and_exit to kthread_complete_and_exit Eric W. Biederman
2021-12-08 20:25 ` [PATCH 09/10] kthread: Ensure struct kthread is present for all kthreads Eric W. Biederman
2021-12-22 18:19 ` Nathan Chancellor
2021-12-22 18:30 ` Eric W. Biederman
2021-12-22 18:46 ` Nathan Chancellor
2021-12-22 23:22 ` Eric W. Biederman
2021-12-23 0:37 ` Nathan Chancellor
2021-12-23 1:44 ` Linus Torvalds
2021-12-23 3:34 ` Eric W. Biederman
2021-12-23 5:19 ` [PATCH] kthread: Generalize pf_io_worker so it can point to struct kthread Eric W. Biederman
2021-12-23 17:20 ` Linus Torvalds
2022-01-07 3:59 ` [PATCH 09/10] kthread: Ensure struct kthread is present for all kthreads Al Viro
2022-01-08 18:20 ` Eric W. Biederman
2021-12-08 20:25 ` [PATCH 10/10] exit/kthread: Move the exit code for kernel threads into struct kthread Eric W. Biederman
2022-01-07 3:22 ` Al Viro
2021-12-13 22:50 ` [PATCH 0/8] signal: Cleanup of the signal->flags Eric W. Biederman
2022-01-03 21:30 ` [PATCH 00/17] exit: Making task exiting a first class concept Eric W. Biederman
2022-01-03 21:32 ` [PATCH 01/17] exit: Remove profile_task_exit & profile_munmap Eric W. Biederman
2022-01-04 7:38 ` Christoph Hellwig
2022-01-07 3:48 ` Al Viro
2022-01-08 16:10 ` Eric W. Biederman
2022-01-03 21:32 ` [PATCH 02/17] exit: Coredumps reach do_group_exit Eric W. Biederman
2022-01-03 21:32 ` [PATCH 03/17] exit: Fix the exit_code for wait_task_zombie Eric W. Biederman
2022-01-03 21:32 ` [PATCH 04/17] exit: Use the correct exit_code in /proc/<pid>/stat Eric W. Biederman
2022-01-03 21:33 ` [PATCH 05/17] taskstats: Cleanup the use of task->exit_code Eric W. Biederman
2022-01-03 21:33 ` [PATCH 06/17] ptrace: Remove second setting of PT_SEIZED in ptrace_attach Eric W. Biederman
2022-01-03 21:33 ` [PATCH 07/17] ptrace: Remove unused regs argument from ptrace_report_syscall Eric W. Biederman
2022-01-03 21:33 ` [PATCH 08/17] ptrace/m68k: Stop open coding ptrace_report_syscall Eric W. Biederman
2022-01-10 15:26 ` Geert Uytterhoeven
2022-01-10 16:20 ` Al Viro
2022-01-10 16:25 ` Al Viro
2022-01-10 17:54 ` Geert Uytterhoeven
2022-01-10 20:37 ` Al Viro
2022-01-10 21:18 ` Eric W. Biederman
2022-01-11 1:33 ` Michael Schmitz
2022-01-11 22:42 ` Finn Thain
2022-01-12 0:20 ` Michael Schmitz
2022-01-12 3:32 ` Finn Thain
2022-01-12 7:54 ` Michael Schmitz
2022-01-12 7:55 ` Geert Uytterhoeven
2022-01-12 8:05 ` Michael Schmitz
2022-01-03 21:33 ` [PATCH 09/17] ptrace: Move setting/clearing ptrace_message into ptrace_stop Eric W. Biederman
2022-01-03 21:33 ` [PATCH 10/17] ptrace: Return the signal to continue with from ptrace_stop Eric W. Biederman
2022-01-03 21:33 ` [PATCH 11/17] ptrace: Separate task->ptrace_code out from task->exit_code Eric W. Biederman
2022-01-03 21:33 ` [PATCH 12/17] signal: Compute the process exit_code in get_signal Eric W. Biederman
2022-01-03 21:33 ` Eric W. Biederman [this message]
2022-01-03 21:33 ` [PATCH 14/17] signal: Remove zap_other_threads Eric W. Biederman
2022-01-03 21:33 ` [PATCH 15/17] signal: Add JOBCTL_WILL_EXIT to mark exiting tasks Eric W. Biederman
2022-01-03 21:33 ` [PATCH 16/17] signal: Record the exit_code when an exit is scheduled Eric W. Biederman
2022-01-03 21:33 ` [PATCH 17/17] signal: Always set SIGNAL_GROUP_EXIT on process exit Eric W. Biederman
2022-03-09 0:15 ` [PATCH 00/13] Removing tracehook.h Eric W. Biederman
2022-03-09 20:58 ` Linus Torvalds
2021-12-13 22:53 ` [PATCH 1/8] signal: Make SIGKILL during coredumps an explicit special case Eric W. Biederman
2022-01-04 6:30 ` Dmitry Osipenko
2022-01-04 16:18 ` Eric W. Biederman
2022-01-05 19:58 ` Eric W. Biederman
2022-01-05 21:39 ` Dmitry Osipenko
2022-01-08 18:13 ` Eric W. Biederman
2022-01-08 18:15 ` [PATCH 1/2] signal: Have prepare_signal detect coredumps using signal->core_state Eric W. Biederman
2022-01-08 18:15 ` [PATCH 2/2] signal: Make coredump handling explicit in complete_signal Eric W. Biederman
2022-01-11 8:59 ` [PATCH 1/8] signal: Make SIGKILL during coredumps an explicit special case Dmitry Osipenko
2022-01-11 17:20 ` Eric W. Biederman
2022-01-18 17:30 ` Dmitry Osipenko
2022-01-18 17:52 ` Eric W. Biederman
2022-01-18 18:01 ` Dmitry Osipenko
2022-01-04 18:44 ` Linus Torvalds
2022-01-04 19:47 ` Eric W. Biederman
2022-01-08 19:13 ` Heiko Carstens
[not found] ` <87ilurwjju.fsf@email.froward.int.ebiederm.org>
[not found] ` <87o84juwhg.fsf@email.froward.int.ebiederm.org>
2022-01-10 23:00 ` Olivier Langlois
2022-01-11 17:28 ` Eric W. Biederman
2022-01-11 18:51 ` Eric W. Biederman
2022-01-11 19:19 ` Linus Torvalds
2022-01-15 0:12 ` Eric W. Biederman
2022-01-15 19:23 ` Olivier Langlois
2022-01-17 16:09 ` Eric W. Biederman
2022-01-17 18:46 ` io_uring truncating coredumps Eric W. Biederman
2022-01-18 4:23 ` Linus Torvalds
2022-01-26 15:06 ` [PATCH 1/8] signal: Make SIGKILL during coredumps an explicit special case Olivier Langlois
2021-12-13 22:53 ` [PATCH 2/8] signal: Drop signals received after a fatal signal has been processed Eric W. Biederman
2021-12-13 22:53 ` [PATCH 3/8] signal: Have the oom killer detect coredumps using signal->core_state Eric W. Biederman
2021-12-13 22:53 ` [PATCH 4/8] signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process Eric W. Biederman
2021-12-13 22:53 ` [PATCH 5/8] signal: Remove SIGNAL_GROUP_COREDUMP Eric W. Biederman
2021-12-13 22:53 ` [PATCH 6/8] coredump: Stop setting signal->group_exit_task Eric W. Biederman
2021-12-13 22:53 ` [PATCH 7/8] signal: Rename group_exit_task group_exec_task Eric W. Biederman
2021-12-13 22:53 ` [PATCH 8/8] signal: Remove the helper signal_group_exit Eric W. Biederman
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